1. Field of the Invention
This invention relates to an improvement in the method of finding water leakage positions within a containment vessel for a nuclear reactor, for example, with a device for monitoring the operating conditions of the nuclear reactor.
2. Description of the Prior Art
The containment vessel for the nuclear reactor has in its interior the so-called "primary coolant pipe arrangement" extended in all directions. The total length of extension of the pipe arrangement becomes considerably long and moreover the coolant flowing inside the tube is at a high temperature and high pressure, on account of which there is high probability of water leaking from joints and seams of the pipes. Such water leakage should be discovered as early as possible by constant inspection, and, if found, be repaired while the quantity of leakage is still small.
However, the interior of the containment vessel is generally at a high radiation level, which makes it difficult for inspecting personnel to come in and out of the containment vessel freely. In order to avoid such a risky situation, there have been contemplated various unmanned or remote inspection methods.
FIG. 1 of the accompanying drawing illustrates one example of a conventional remote inspection method, in which a numeral 1 refers to a pipe arrangement which is to be inspected, a reference numeral 2 designates a valve to be inspected, 3 denotes a handle of the valve, 4 a connection between the pipe arrangement and the valve, 5 a television camera for industrial use (hereinafter abbreviated as "ITV"), and 6 refers to illuminating lamps, all being installed in the containment vessel (not shown in the drawing).
With the remote inspection system of the above-mentioned construction, the inspecting personnel (not shown in the drawing) is able to watch the pipe arrangement 1, the valve 2, and so forth from the exterior of the containment vessel by use of a television image pick-up device (not shown in the drawing) connected with the ITV 5, and he is also able to adjust direction, brightness, and other factors of the ITV 5 for the purpose of inspection by means of a remote control device (not shown in the drawing).
While the conventional method of inspecting the water leakage within the containment vessel has been done as mentioned above, such inspection of the water leaking points of the pipe within the containment vessel of a large volume takes very many hours and moreover it is considerably difficult, for the reasons that such possible leaking points of the water leakage are as many as a few hundreds or more, that since the pipes are arranged in a three-dimensional network structure, the water leakage points of the pipe is likely to be hidden behind other installations, and that the sight of the ITV is narrow, and others.